The complex soical organizations of some primates share several basic features with those of certain birds. Among the most important of these is helping behavior. Insight into the evolution of such shared features can often be obtained more conveniently in birds than primates. Biological theories of social organization that are based on kinship have excited much recent interest, but data on kinship in relation to helping behavior remain vague. The application and testing of kinship techniques and theories require long-term studies on indiviudals of known age and parents. It is proposed to take advantage of the existence of a color-banded population of jays, many of whom are of known age and ancestry, to determine accurately the closeness and variability of genetic relatedness in helper-recipient relationships. The observed genealogical relationships will be compared with observed helping behavior in the feeding of nestlings. These data will enable a test of a simple hypothesis arising from Hamilton's theory, namely, that helpers are closely related genetically to recipients. The fraction of total feeding visits to nestlings by a each individual will be compared with the genetic relatedness of each feeder to the nestlings. Variations in the correlation between these two variables will be described and evaluated. In addition, a wealth of data on the ecology of helping behavior in babblers and jays already at hand will be analyzed. Analyses will be done by computer, and will include reproduction, survival, dispersal, means of entry into the breeding population, helping relationships, genetic relatedness, flock size, flock composition, and ecological variables related to weather, vegetation, elevation, and food.